Several GWAS have now been conducted in COPD and several genes have been found to be associated with the development of this condition, the most common and strongly associated being HHIP (hedgehog-interacting protein) (30), CHRNA3 (cholinergic receptor, nicotinic, alpha 3) (30), IREB2 (iron responsive element binding protein 2) (10), and FAM13A (family with sequence similarity 13, member A) (8). Here, HHIP is linked to chronic obstructive pulmonary disease.